<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>体验</title>
</head>

<body>
<script>
    function writeCode(str) {
      const el = document.querySelector('body');
      el.innerHTML = str;
    }
</script>
</body>

</html>